Alyssum

( al - LISS - sum )

At-A-Glance Information

This genus of flowering perennials commonly called Madwort can take full sun or light shade and need regular water. They are native to the Mediterranean, and form mounds of green leaves that produce yellow blooms in terminal clusters. They are great for borders and rock gardens, and thrive in poor, rocky soil as long as it is well-draining. 

Alyssum Species and Varietals

The genus Alyssum includes over one hundred species, and is part of the family Brassicaceae. Note that the plant commonly called Sweet Alyssum is actually a close relative in the genus Lobularia, and is therefore not included in the list of species below. Alyssum grows best in zones 1-24. To find your zone, click here: Zone Map.

Alyssum alyssoides (Pale Madwort, Yellow Alyssum)
This species is native to Eurasia, and has naturalized itself (and in some cases has become invasive) in many areas, including the western United States. It is at home in fields, docks, and sandy areas. It reaches between 12 and 16 inches tall and produces yellow flowers which fade to white with age from May through July.

Alyssum artvinense (Artvinian Alyssum)
This species is native to northeastern Turkey where it is found on stony sloped areas and forest clearings. This type of Alyssum is considered endangered, threatened by habitat loss and degradation from dams, roads, and erosion.

Alyssum dagestanicum (Dagestanian Alyssum)
This species is native to Russia and the Caucasus Mountains, and is endangered thanks to over-grazing and cropland development in its home range.

Alyssum montanum (Alyssum gmelinii)
This garden variety of Alyssum reaches up to 8 inches in height and 1.5 feet wide, and produces clusters of fragrant yellow flowers. Leaves are grey-green. Varietal 'Berggold' ('Mountain Gold') is the most popular and widely sold type of this species.
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​Alyssum saxatile (Aurinia saxatilis)
This type of Alyssum is called 'Basket of Gold' and will attract beneficial insects to your yard. It is a relative of mustard, and hails from the mountains of central and southern Europe and Turkey. These have grey leaves (that in some varieties are variegated) and form a spreading evergreen mound 8-12 inches tall. Dense clusters of single or double yellow to apricot flowers bloom in spring and early summer. As long as drainage is good, does not mind poor soils. Self sows, and is generally hardy but will be taken out by extreme cold.

Alyssum serpyllifolium (Alyssum djurdjurae) (Thyme-Leaved Alison)
Native to the western Mediterranean, this species does well in rock gardens. Flowers are yellow, and stems and leaves are green. This plant has the power to detoxify soil caused by rock weathering or industrialization.

Alyssum propinquum
This yellow-flowered plant is native to southern Turkey and reaches 3 inches tall and 12 inches wide. This species is wonderful in rock gardens.

​Alyssum pulvinare (Alyssum thracicum) (Madwort)
This species is at home on rocky ledges and grassy slopes and forms a tuft of greenery 2.5-6 inches tall. It is native to central Greece, Macedonia, and Romania. Yellow flowers bloom in May and June.

Alyssum wulfenianum (Madwort)
This is a trailing plant that gets to about 1.5 feet wide with fleshy, silvery leaves and profuse yellow flowers. This species is native to the Alps, and has a popular cultivar called 'Golden Spring'. These plants prefer dry, rocky soils.

Caring for Alyssum

Alyssum is easy to grow from seed in the garden, though it is more common to purchase from nurseries as a potted transplant. They love full sun and well-draining soil. They'll grow well in rocky soil, and do not like to be kept in wet soil. Alyssum are great choices for containers, and have a slight spilling effect when planted in front of other upright plants. Alyssum does not need to be deadheaded, but occasional pruning will encourage a more bushy habit. Over the wintertime, the plants tend to get a little leggy, and can either be pruned the following spring or be replaced. The best time to plant Alyssum is in the springtime, after the last chance of frost has passed. 

Propagation

The best way to propagate Alyssum is by seed. To complete this process, you'll need well-draining soil and a pot or tray. Once you've gathered your materials, follow these steps:
  1. Purchase your Alyssum seeds or harvest your seeds from an existing plant. Seeds on Alyssum will be ready for harvest in late summer to fall, when most of the blooms have faded and they produce their seeds. See the images below for reference.
  2. Prepare your pot or growing tray with soil and water it to ensure that good drainage is occurring, or prepare your planting bed outdoors by amending soil with new, nutrient rich soil. Seeds can be started indoors at any time of the year, but it is best to start them between the months of January and August. If you are direct-sowing your seeds in the ground, plant them between December and March. Place your seeds in the pot, tray, or on the soil outside, and cover them with more soil.
  3. Carefully water your seeds; it may be best to use a spray nozzle to 'rain' the top soil or use a spray bottle for your pot to avoid disturbing your little seeds. 
  4. The seeds should begin to produce sprouts in around eight to ten days. Once this occurs, spread seedlings out to be six inches apart.
Alyssum seed pods will look similar to this.
Alyssum seeds ready to be planted.

Problems and Pests

The Alyssum plant is relatively easy to grow and does not have many issues, though it is susceptible to a few problems, including:
  • Root Rot
  • Stem Rot
  • Cyclamen Mite
  • Foliage-Feeding Caterpillars
  • Botrytis Blight
  • Clubroot
  • Downy Mildew
  • Fasciation
For more information on how to prevent and eradicate these issues, see the following links:
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Gallery

Alyssum can really be grown anywhere, including in small rock crevices.
Botanical art of Alyssum montanum.
Alyssum saxatile spills over walls and container walls.

Videos

All about Alyssum saxatile.
A great video about planting and caring for Alyssum.

Resources

Tips on Growing Hardy Alyssum Flowers
Managing Pests in Gardens: Floriculture: Alyssum
5 Tips for Growing Alyssum
Wikipedia: Alyssum
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 148, Alyssum
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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